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Sunday Times Teaser 2731 – Snarl Up

by Michael Fletcher

Published: 25 January 2015 (link)

I had to drive the six miles from my home into the city centre. The first mile was completed at a steady whole number of miles per hour (and not exceeding the 20mph speed limit). Then each succeeding mile was completed at a lower steady speed than the previous mile, again at a whole number of miles per hour.

After two miles of the journey my average speed had been a whole number of miles per hour, and indeed the same was true after three miles, after four miles, after five miles, and at the end of my journey.

How long did the journey take?

3 Comments Leave one →
  1. Brian Gladman permalink

  2. Don Thompson permalink

    Searching to see if anyone had info on this puzzle. I know nothing of programming – trying it longhand and cannot find a solution other than one starting at 24mph – does the programme find one starting below or at 20mph?

  3. Brian Gladman permalink

    Hello Don,

    Yes, the solution is as follows:

    Journey time was 120 minutes, leg speeds = (20, 12, 6, 5, 2, 1) mph.

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